This was my question as well. I have seen it a lot. I understand it for people that have vim ingrained in their fingers (muscle memory).

I do not understand the reason for this at all for people who don't know vim. There are plenty of other editors that are just as feature rich, if not more so (Sublime and PSPad come to mind). Also, if you need the GUI based macvim, you lose the most important feature of vim and the actual main reason for its popularity today: the ability to edit files locally or remotely inside a shell that supports only text.

Then again, choosing inferior technology is actually quite common these days, as the widespread use of Rails easily demonstrates.